A look at developments surrounding North Korea’s nuke test

South Korea is limiting entry to an industrial park in North Korea jointly run by two Koreas in its first concrete action since Pyongyang said it had carried out a successful hydrogen bomb test.

U.S analysts tracking China-North Korea relations think China would not squeeze Kim Jong-un’s regime to the point where it may collapse and cause turmoil at its borders. China’s Environmental Protection Ministry has also been evaluating the impact of the test and analyzing the radiation data collected along the border. South Korea’s Defense Ministry couldn’t confirm the reports.

In a separate development Vice Admiral Joseph Aucoin, commander of the U.S. 7th Fleet based in Yokosuka, Japan, said the Navy was watching North Korea closely. North Korea also vowed that it will not transfer its nuclear capabilities to other parties. The government will allow only South Korean businessmen and workers directly involved in the operation of the factories to cross the Korean border, according to the official.

Kerry told reporters in Washington on Thursday that America “respected” Beijing’s special approach towards North Korea, and in particular sanctions imposed on Pyongyang.

“Our military is at a state of full readiness, and if North Korea wages provocation, there will be firm punishment”.

“There is a high possibility that North Korea could react in an ultra-harsh manner by regarding South Korea’s decision as ruining the birthday celebration”, said Cheong Seong-chang, a senior researcher at the Sejong Institute, Yonhap reported.

US Secretary of State John Kerry said he made clear in a phone call with Chinese Foreign Minister Wang Yi that China’s approach to North Korea had failed.

South Korea responded on Friday to a nuclear test conducted by its northern neighbor by blasting Korean pop music toward the isolated rogue nation, an official said.

While a nuclear test had always been expected, North Korea’s assertion that it exploded a hydrogen device, much more powerful than an atomic bomb, came as a surprise.

South Korea is preparing to launch the same anti-North propaganda campaign that brought the two to the brink of war past year.

Although North Korea claimed that the underground blast Tuesday was a thermonuclear hydrogen bomb, the U.S., South Korea and major allies have cast doubt on the claim.

Since North Korea’s announcement of the nuclear test this week, world powers are carefully planning their responses.

“China is not going to like that reality”, DeThomas said.

Fusion is the main principle behind the hydrogen bomb, which can be hundreds of times more powerful than atomic bombs that use fission. However, it will likely take several days to determine more precisely what kind of device was set off as a variety of sensors, including “sniffer planes”, collect evidence. North Korea’s state TV announces hours later that scientists have achieved “perfect success” in testing a “miniaturized” H-bomb.